SAT Subject Physics Practice Question 50: Answer and Explanation
7. A satellite is currently orbiting Earth in a circular orbit of radius R; its kinetic energy is K1. If the satellite is moved and enters a new circular orbit of radius 2R, what will be its kinetic energya?
Correct Answer: B
The gravitational pull by the earth provides the centripetal force on the satellite, so . This gives , so the kinetic energy K of the satellite is inversely proportional to R. Therefore, if R increases by a factor of 2, then K decreases by a factor of 2.